honestly, i'd most likely never turn up at any Eco Event.
gathering people to certain places to watch entertaining acts? waste of electricity, resources like petrol, and most likely getting rubbish strewn all over etc etc.
and gathering large amounts of people into one place causes build-up of green house gases.
anyways most of these events are just designed to pull people to businesses in the area. celebrating saving the ecology by switching off lights for an hour? like that'll get people interested in conserving nature
just my 2 cents from the point of view of the Earth Hour events